The present invention relates to an image read apparatus and an image read method, wherein the image read apparatus is provided in an image forming apparatus such as an electronic copying machine and optical image information from a document is received by a 4-division photoelectric conversion element to read an image of the document.
In a conventional image forming apparatus such as an electronic copying machine, in order to increase an image read rate, a pre-processing system is constituted by using a 4-channel output CCD (4-division photoelectric conversion element) and an amplifier (AMP).
In this pre-processing system, in order to reduce influence upon image data due to a difference in signal transmission paths, a left odd output component a1 and a right odd output component a2 of a 4-channel output of the CCD (one line being divided into left and right components, and each of the left and right components being divided into odd components and even components) are amplified by an amplifier A, and a left even output component b1 and a right even output component b2 are amplified by an amplifier B. Thus, a variance and an influence of the amplifiers between left and right sides are reduced.
A correction means is provided to correct one of the odd output components a1 and a2 amplified by the amplifier A so that the signal levels of both components at points corresponding to the center of the signal line may be equalized. In addition, another correction means is provided to correct one of the even output components b1 and b2 amplified by the amplifier B so that the signal levels of both components at points corresponding to the center of the signal line may be equalized. Thus, the image data is corrected and the signal sequence of image data (4-channel outputs of the CCD) is regulated.
The outputs of the CCD, however, are analog outputs and susceptible to crosstalk on the circuit board, crosstalk in the LSI (amplifier), or influence of switching at the time of multiplexing. If the image read rate is to be further increased, such influence may occur more seriously. Under the circumstances, if the left and right odd output components of the 4-channel output of the CCD and the left and right even output components are amplified by the respective amplifiers, these output components may be adversely affected by crosstalk on the circuit board, crosstalk in the LSI (amplifier) or switching at the time of multiplexing. Consequently, an output image may become a ghost image due to right-and-left variance.
The object of the present invention is to provide an image reading apparatus capable of reading an output image with high fidelity to an original, without influence of switching at the time of crosstalk multiplexing between output signals in a case where a 4-division photoelectric conversion element is used.
To achieve the object, according to an aspect of the present invention, there is provided an image reading apparatus comprising:
a 4-division photoelectric conversion element for receiving light at four division image-feed areas consisting of an odd area located on a left side in a main scan direction, an odd area on a right side in the main scan direction, an even area on the left side in the main scan direction, and an even area on the right side in the main scan direction;
a first amplifier for synthesizing and amplifying output signals from the left-side odd area and left-side even area of the four division areas of the 4-division photoelectric conversion element which has received light;
a second amplifier for synthesizing and amplifying output signals from the right-side odd area and right-side even area of the four division areas of the 4-division photoelectric conversion element which has received light; and
a correction circuit for performing right/left correction between an output from the first amplifier which has synthesized the output signals from the left-side areas and an output from the second amplifier which has synthesized the output signals from the right-side areas.
According to another aspect of the invention, there is provided an image reading apparatus comprising:
a 4-division photoelectric conversion element for receiving light at four division image-feed areas consisting of an odd area located on a left side in a main scan direction, an odd area on a right side in the main scan direction, an even area on the left side in the main scan direction, and an even area on the right side in the main scan direction;
a first selector for selecting one of output signals from the left-side even area and right-side odd area of the four division areas of the 4-division photoelectric conversion element which has received light;
a first amplifier for synthesizing and amplifying an output signal from the left-side even area and one of the output signals, which has been selected by the first selector, from the left-side even area and right-side odd area of the four division areas of the 4-division photoelectric conversion element which has received light;
a second amplifier for synthesizing and amplifying an output signal from the right-side even area and one of the output signals, which has been selected by the first selector, from the left-side even area and right-side odd area of the four division areas of the 4-division photoelectric conversion element which has received light;
a first bus width conversion circuit for dividing the output signal from the left-side odd area amplified and synthesized by the first amplifier, and one of the output signals, which has been selected by the first selector, from the left-side even area and the right-side odd area;
a second bus width conversion circuit for dividing the output signal from the right-side even area amplified and synthesized by the second amplifier, and one of the output signals, which has been selected by the first selector, from the left-side even area and the right-side odd area;
a second selector for selecting one of the output signals, which has been divided by the first bus width conversion circuit, from the left-side even area and the right-side odd area, and one of the output signals, which has been divided by the second bus width conversion circuit, from the left-side even area and the right-side odd area;
a correction circuit for correcting left-side and right-side output signals with respect to the output signal from the left-side odd area, which has been divided by the first bus width conversion circuit, one of the output signals from the left-side even area and right-side odd area, which has been selected by the second selector, the output signal from the right-side even area, which has been divided by the second bus width conversion circuit, and one of the output signals from the left-side even area and right-side odd area, which has been selected by the second selector; and
a control circuit for controlling the output signals selected by the first selector and the second selector.
According to still another aspect of the invention, there is provided an image reading method comprising the steps of:
providing a 4-division photoelectric conversion element for receiving light at four division image-feed areas consisting of an odd area located on a left side in a main scan direction, an odd area on a right side in the main scan direction, an even area on the left side in the main scan direction, and an even area on the right side in the main scan direction;
synthesizing and amplifying output signals from the left-side odd area and left-side even area of the four division areas of the 4-division photoelectric conversion element which has received light;
synthesizing and amplifying output signals from the right-side odd area and right-side even area of the four division areas of the 4-division photoelectric conversion element which has received light; and
performing right/left correction between an output obtained by synthesizing and amplifying the output signals from the left-side areas and an output obtained by synthesizing and amplifying the output signals from the right-side areas.
According to still another aspect of the invention, there is provided an image reading method comprising the steps of:
providing a 4-division photoelectric conversion element for receiving light at four division image-feed areas consisting of an odd area located on a left side in a main scan direction, an odd area on a right side in the main scan direction, an even area on the left side in the main scan direction, and an even area on the right side in the main scan direction; and
selecting one of two modes:
one of the two modes being such that output signals from the left-side odd area and left-side even area of the four division areas of the 4-division photoelectric conversion element which has received light are synthesized and amplified, and output signals from the right-side even area and left-side even area are synthesized and amplified, and
the other of the two modes being such that output signals from the left-side odd area and right-side odd area of the four division areas of the 4-division photoelectric conversion element which has received light are synthesized and amplified, and output signals from the right-side even area and right-side odd area are synthesized and amplified.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.